Load bearing panel member

ABSTRACT

A load bearing panel member having a first portion, a second portion, and an appearance surface portion is formed by injection molding such that the first portion includes a plurality of ribs forming a grid pattern on the first portion and another plurality of ribs extending toward the periphery of the first portion which may be non-orthogonal to each other and to the ribs forming the grid pattern. An internal channel may be formed within each of the non-orthogonal ribs by injecting a gas into the rib during the molding process forming the panel. An appearance surface portion attached to the first portion and second portion of the panel member forms an integral hinge between the first and second portions of the panel member. The panel member may be configured as a floor panel of a vehicle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of expired U.S. ProvisionalApplication No. 60/691,790 filed Jun. 17, 2005, U.S. Pat. No. 8,221,673issued Jul. 17, 2012, and U.S. Non-Provisional application Ser. No.13/494,174 filed Jul. 12, 2012, each hereby incorporated by reference inits entirety.

TECHNICAL FIELD

The present invention is drawn to a load bearing panel member formed bya method of injection molding.

BACKGROUND

There are numerous known systems for plastic injection molding. Inconventional plastic injection molding systems, plastic pellets aremelted in an injection molding machine and advanced by a screw ramthrough an injection nozzle and into a mold cavity. The mold cavity ispreferably formed between two mold halves. The molten plastic materialin the cavity is allowed to cool and harden in the cavity. When theplastic material has cooled and sufficiently hardened, the two halves ofthe mold are separated or opened and the part is removed, typically byone or more ejector pins.

Some injection molding systems utilize a gas in the injection moldingprocess and are commonly known as “gas-assisted injection molding”systems. In these systems, the gas is injected into the molten plasticmaterial through the plastic injection nozzle itself, or through one ormore pin mechanisms strategically positioned in the mold. It is alsopossible to inject the gas directly into the molten plastic in thebarrel of the injection molding machine. The gas, which typically is aninert gas such as nitrogen, is injected under pressure and forms one ormore hollow cavities or channels in the molded part.

Gas-assisted injected molding produces a structure having a hollowinterior portion which results in saving weight and material, therebyreducing costs. The pressurized gas applies an outward pressure to forcethe plastic against the mold surfaces while the article solidifies. Thishelps provide a better surface on the molded article and reduces oreliminates sink marks and other surface defects. The use of pressurizedgas also reduces the cycle time as the gas is introduced and/or migratesto the most fluent inner volume of the plastic and replaces the plasticin those areas which would otherwise require an extended cooling cycle.The pressure of the gas pushing the plastic against the mold surfacesfurther increases the cooling effect of the mold on the part, thussolidifying the part in a faster manner and reducing the overall cycletime.

SUMMARY

The present invention provides a method for producing a structural orload bearing injection molded panel member. According to a preferredembodiment, the panel member is a floor panel for a van havingretractable rear seats wherein the panel member is adapted to cover therear seats when fully retracted and act as a load floor. The panelmember preferably includes a first portion, a second portion and aninterior surface portion. The present invention will hereinafter bedescribed according to the preferred embodiment wherein the interiorsurface portion is a carpet material; however, it should be appreciatedthat according to alternate embodiments the interior surface portioncould also include, for example, a vinyl material or a textile material.

The preferred method of the present invention includes placing thecarpet material into a mold cavity configured to produce the panelmember. The mold cavity preferably includes a first chamber adapted toform the first portion of the panel member, and a second chamber adaptedto form the second portion of the panel member. After the carpetmaterial is inserted into the mold, molten plastic material andpressurized gas are injected into the first chamber of the mold cavity.After the molten plastic material is injected into the first chamber ofthe mold, molten plastic material is injected into the second chamber ofthe mold cavity. A sequential gating process is used to achieve thissequence of operations. The molten plastic is then cooled until itsolidifies. After the molten plastic is sufficiently cooled, thepressurized gas is vented and the panel member is removed from the mold.

It should be appreciated that the order in which the steps of thepreferred embodiment are performed may be varied according to alternateembodiments. For example, according to one alternate embodiment of thepresent invention, the molten plastic material may be injected into thesecond chamber of the mold cavity before molten plastic material isinjected into the first chamber of the mold cavity. According to yetanother alternate embodiment, molten plastic may be injected into thefirst and second chambers of the mold cavity simultaneously.

The present invention also provides a structural or load bearing panelmember and a product by process. The load bearing panel memberpreferably includes a generally rectangular first portion, a generallyrectangular second portion, and a carpet material. The carpet materialis attached to the first portion and the second portion such that thecarpet material forms an integral or living hinge at a gap therebetween.The first portion of the panel member defines a plurality of solidhorizontally disposed ribs and a plurality of solid vertically disposedribs. The first portion of the load bearing panel member also includes aplurality of hollow ribs formed by the gas assisted injection moldingprocess. The hollow ribs are generally located around the periphery ofthe first portion of the load bearing panel member as well as in anX-shape originating at the center of the first portion and extendingtoward the corners thereof. The solid ribs and hollow ribs are adaptedto increase strength and rigidity and provide substantial structural orload-bearing capability

The above features and advantages and other features and advantages ofthe present invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom view of a load bearing panel member in accordancewith the present invention;

FIG. 2 is a block diagram illustrating a method of the presentinvention;

FIG. 3 is a sectional view of the panel member taken along line A-A ofFIG. 1;

FIG. 4 a is a schematic sectional view of an injection molding nozzleand a plurality of valves; and

FIG. 4 b is a schematic plan view of a mold cavity.

DESCRIPTION

Referring to the drawings, wherein like reference numbers refer to likecomponents, FIG. 1 shows a panel member 10 produced according to amethod of the present invention. The panel member 10 will hereinafter bedescribed as a floor panel for a van having retractable rear seats (notshown), wherein the panel member 10 is adapted to cover the rear seatswhen the seats are fully retracted and also to act as a load floor. Itshould be appreciated, however, that the method of the present inventionmay be implemented to produce other conventional panel members as well.

The panel member 10 includes a generally rectangular first portion 12, agenerally rectangular second portion 14, and an interior or appearancesurface portion 16 (shown in FIG. 3). The present invention willhereinafter be described according to the preferred embodiment whereinthe interior surface portion 16 is carpet material; however, it shouldbe appreciated that according to alternate embodiments the interiorsurface portion 16 could also include, for example, a vinyl material ora textile material. According to a preferred embodiment, the carpetmaterial 16 is a polypropylene material with a polyester backing Thecarpet material 16 is attached to the first portion 12 and the secondportion 14 such that the carpet material 16 forms an integral or livinghinge 18 at a gap 19 between the first portion 12 and the second portion14. The first portion 12 of the panel member 10 defines a plurality ofsolid horizontally disposed ribs 20 and solid vertically disposed ribs21. The solid ribs 20 and 21 are normal to each other so as to increasestrength and rigidity and provide substantial load-bearing capability.According to a preferred embodiment of the present invention, the secondportion 14 of the panel member 10 includes a plurality of up-standingclip attach members 22.

The clip attach members 22 preferably each retain a metallic attachmentclip (not shown) configured to mount the second portion 14 of the panelmember 10 to a seat assembly (not shown). When the seat assembly is inan upright position, the hinge 18 allows the second portion 14 of thepanel member 10 to fold underneath the first portion 12 and below theseat.

When the seat assembly (not shown) is fully retracted, the first portion12 of panel member 10 is rotatable about the integral hinge 18 from anopen position exposing the seat assembly to a closed position at whichthe seat assembly is covered. When the seat assembly is fully retractedand the first portion 12 of panel member 10 is in the closed position,the carpet material 16 (shown in FIG. 3) is exposed and the seatassembly is completely hidden. In this manner, the panel member 10 isadapted to provide an aesthetically pleasing carpeted interior when theseat assembly is retracted, and also provide substantial floor-strength.

Referring to FIG. 2, a method for manufacturing the panel member 10according to the present invention is shown. At step 50, the carpetmaterial 16 is placed into a mold cavity 70 (shown in FIG. 4 b)configured to produce the panel member 10. Optionally, at step 50, metalinserts such as bars and/or tubes (not shown) can also be placed intothe mold cavity 70 with the carpet material 16 to produce a panel member10 with increased strength and rigidity. The mold cavity 70 of thepresent invention preferably includes a first chamber 72 (shown in FIG.4 b) adapted to form the first portion 12 of the panel member 10, and asecond chamber 74 (shown in FIG. 4 b) adapted to form the second portion14 of the panel member 10. The first and second chambers 72, 74 arepreferably separated by an insert or feature 75 (shown in FIG. 4 b)configured to produce the integral hinge 18 (shown in FIG. 3). At step52, molten plastic material 76 (shown in FIG. 4 a) is injected into thefirst chamber 72 of the mold cavity 70. The molten plastic material 76is preferably injected in a conventional manner, such as, for example,by a reciprocating screw type injection device (not shown), through aninjector nozzle 40 (shown in FIG. 4 a), through a valve gate 42 a (shownin FIG. 4 a), and into the first chamber 72 of the mold cavity 70.

At step 54, an inert gas 80 (shown in FIG. 4 b) such as nitrogen isinjected into the first chamber 72 of the mold cavity 70 (shown in FIG.4 b) through a plurality of gas pins 82 (shown in FIG. 4 b) positionedat locations predefined by the desired locations of the hollow ribs 30.The gas 80 preferably does not mix with the molten plastic material 76,but takes the path of least resistance through the less viscous portionsof the plastic melt. The molten plastic 76 is therefore pushed againstthe wall portions of the mold cavity 70, which forms channels 31 andproduces the hollow ribs 30 (shown in FIGS. 1 and 3).

Referring to FIG. 3, a sectional view taken through section A-A of FIG.1 is shown. It can be seen in FIG. 3 that the hollow ribs 30 define aninternal Chanel 31 through which the gas is injected. Referring again toFIG. 1, the gas 80 (shown in FIG. 4 b) is preferably injected throughthe gas pins 82 (shown in FIG. 4 b) into the first portion 12 of thepanel member 10 at the gas injection locations 32. According to apreferred embodiment, the hollow ribs 30 are generally located aroundthe periphery of the first portion 12 of the panel member 10 as well asin an X-shape originating at the center of the first portion 12 andextending toward the corners thereof. It has been observed that thehollow ribs 30 formed in the manner described increase the rigidity andstrength of the first portion 12 of the panel member 10. The increasedstrength and rigidity is particularly advantageous for the preferredembodiment wherein the panel member 10 is implemented as a load bearingfloor panel.

Referring again to FIG. 2, at step 56 molten plastic material 76 (shownin FIG. 4 a) is injected into the second chamber 74 of the mold 70(shown in FIG. 4 b). The molten plastic material 76 is preferablyinjected through the injector nozzle 40 (shown in FIG. 4 a), through avalve gate 42 b (shown in FIG. 4 a), and into the second mold chamber74.

A sequential gating process is preferably implemented to performpreviously described steps 52 and 56. Referring to FIGS. 4 a-4 b, thevalve gates 42 a and 42 b, which are adapted to feed the first andsecond mold chambers 72, 74, respectively, are opened using thesequential gating process. In other words, the sequential gating processis implemented to control the timing of the gates 42 a, 42 b and tocoordinate the operation of valve gate 42 b with the operation of valvegate 42 a. According to a preferred embodiment, the valve gates 42 a and42 b are configured to open and close at a predetermined time. Thepredetermined time at which the valve gates 42 a and 42 b open and closeis generally based on the needs of the specific part to be molded andtype of material being used. Alternatively, the valve gates 42 a and 42b may be opened and closed based on the position of a screw typeinjection device (not shown).

Referring again to FIG. 2, at step 58 the molten plastic material 76(shown in FIG. 4 a) that was injected into the first and second chambers72, 74 of the mold cavity 70 (shown in FIG. 4 b) at steps 52 and 56 isallowed to cool and solidify. Thereafter, at step 60, the pressurizedgas 80 (shown in FIG. 4 b) that was injected in to the first chamber 72of the mold cavity 70 at step 54 is allowed to vent through the gas pins82 (shown in FIG. 4 b). At step 62, the finished panel member 10 isremoved from the mold cavity 70.

It should be appreciated that the order in which the steps 50-62 of thepreferred embodiment are performed may be varied according to alternateembodiments. For example, according to one alternate embodiment of thepresent invention, step 56 at which the molten plastic material 76(shown in FIG. 4 a) is be injected into the second chamber 74 (shown inFIG. 4 b) of the mold cavity 70 (shown in FIG. 4 b) may be performedbefore step 52 at which molten plastic material 76 is injected into thefirst chamber 72 (shown in FIG. 4 b) of the mold cavity 70. According toyet another alternate embodiment, steps 52 and 56 may be performedsimultaneously such that molten plastic 76 is injected into the firstand second chambers 72, 74 of the mold cavity 70 simultaneously.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A method of forming a load bearing panel member, the methodcomprising: inserting an appearance surface portion into a mold cavityhaving a first chamber, a second chamber, and a mold feature configuredto separate the first chamber and the second chamber such that theappearance surface portion spans the first and second chambers and themold feature; injecting molten plastic into the first and secondchambers of the mold to form a first portion of the panel member in oneof the first and second chambers and a second portion of the panelmember in the other of the first and second chamber; wherein the one ofthe first and second chambers defines: a first plurality of ribs forminga grid pattern on the first portion; a second plurality of ribspositioned adjacent the periphery of the first portion; a thirdplurality of ribs extending toward the periphery of the first portion,wherein each of the third plurality of ribs is non-orthogonal to anotherof the third plurality of ribs and non-orthogonal to each of the secondplurality of ribs; the method further comprising: forming each of thefirst plurality of ribs as solid ribs; and forming an internal channelwithin each of the second plurality of ribs and each of the thirdplurality of ribs.
 2. The method of claim 1, further comprising: formingan integral hinge between the first and second portions of the panelmember; wherein the integral hinge includes the span of the appearancesurface portion spanning the mold feature.
 3. The method of claim 1,further comprising: injecting pressurized gas into the first chamber ofthe mold cavity and into each rib of the second plurality of ribs in amanner to form a generally cylindrical internal channel in each of thesecond and third plurality of ribs, wherein each generally cylindricalinternal channel is formed in fluid communication with another of thegenerally cylindrical internal channels.
 4. The method of claim 3,further comprising: cooling the molten plastic in first and secondchambers; and venting the pressurized gas from the first chamber of themold cavity.
 5. The method of claim 1, further comprising: sequentiallyopening a plurality of valve gates configured to control the injectionof molten plastic into the first and second chambers of the mold; andinjecting molten plastic into the first and second chambers of the moldaccording to the sequence dictated by the valve gates, wherein theinjecting occurs without expelling plastic from one of the first andsecond chambers into the other of the first and second chambers to formthe first and second portions of the panel member.
 6. The method ofclaim 1, wherein the appearance surface material is a carpet material.7. The method of claim 1, further comprising: inserting a metallicinsert into the mold cavity prior to injecting molten plastic into themold; wherein the metallic insert is configured to increase the rigidityof the panel member.
 8. A method of forming a load bearing panel member,the method comprising: inserting an appearance surface portion of thepanel member into a mold cavity having a first chamber, a secondchamber, and a mold feature configured to separate the first chamber andthe second chamber such that the appearance surface portion spans thefirst and second chambers and the mold feature; and injecting moltenplastic into the first and second chambers of the mold to form a firstportion of the panel member in one of the first and second chambers anda second portion of the panel member in the other of the first andsecond chamber; wherein the one of the first and second chambersdefines: a first plurality of ribs formed orthogonally to a secondplurality of ribs; and a third plurality of ribs obliquely intersectingand non-orthogonal to the first and second plurality of ribs.
 9. Themethod of claim 8, further comprising: forming an internal channelwithin each rib of the third plurality of ribs.
 10. The method of claim8, wherein the first chamber and the second chamber are sufficientlyseparated by the mold feature during the molding process such that theappearance surface portion which spans the mold feature remains uncoatedby molten plastic.
 11. The method of claim 8, further comprising:forming an integral hinge between the first and second portions of thepanel member; wherein the integral hinge includes the span of theappearance surface portion spanning the mold feature.
 12. The method ofclaim 8, further comprising: injecting pressurized gas into the firstchamber of the mold cavity and into each rib of the third plurality ofribs in a manner to form a generally cylindrical internal channel ineach rib of the third plurality of ribs.
 13. A method of forming a loadbearing panel member for a vehicle, the method comprising: inserting anappearance surface portion of the panel member into a mold cavity havinga first chamber, a second chamber, and a mold feature configured toseparate the first chamber and the second chamber such that theappearance surface portion spans the first and second chambers and themold feature; and injecting molten plastic into the first and secondchambers of the mold to form a first portion of the panel member in oneof the first and second chambers and a second portion of the panelmember in the other of the first and second chamber; wherein the one ofthe first and second chambers defines: a first plurality of ribs and asecond plurality of ribs; wherein the first plurality of ribs is formedorthogonally to the second plurality of ribs; the appearance surfaceportion is attached to the first and second plurality of ribs in thefirst portion; and wherein the second portion is attached to theappearance surface portion such that the appearance surface portionforms an integral hinge between the first and second portions of thepanel member.
 14. The method of claim 13, wherein the one of the firstand second chambers defines: a third plurality of ribs generally locatedaround the periphery of the first portion.
 15. The method of claim 14,further comprising: forming a generally cylindrical internal channelwithin at least one rib of the third plurality of ribs.
 16. The methodof claim 13, wherein: the one of the first and second chambers defines afourth plurality of ribs; and the fourth plurality of ribs are obliquelyintersecting and non-orthogonal to the first and second plurality ofribs.
 17. The method of claim 16, further comprising: forming agenerally cylindrical internal channel within each rib of the fourthplurality of ribs.
 18. The method of claim 17, wherein the generallycylindrical internal channel of a first one of the fourth plurality ofribs is in fluid communication with the generally cylindrical internalchannel of a second one of the forth plurality of ribs.
 19. The methodof claim 17, wherein the generally cylindrical internal channel isformed by injecting pressurized gas into each of the fourth plurality ofribs during the molding process forming the panel member.
 20. The loadbearing panel member of claim 13, wherein the appearance surfacematerial is a carpet material.